Adds a few labels for subsequent links.
Gives the next label according to the following rules: - use userProvidedLabel if the user mention it directly; - looks for the next label in the list of labels previously set by user; - constructs a new label using defaultLabel if there are no labels.
Opportunity for extension to hook into method SystemBuilder#toStaticSystem".
Opportunity for extension to hook into method SystemBuilder#toStaticSystem". It can also add some information to extensions map.
An extension that adds easy labelling to System builder.